Evaluation of continuous infusion low-dose 5-azacytidine in the treatment of myelodysplastic syndromes

The treatment of myelodysplastic syndromes (MDS) is both difficult and controversial. In the current study, we evaluated the efficacy of low-dose 5-azacytidine in the treatment of this disorder. Fifteen patients with MDS were entered on study to be treated with 5-azacytidine by continuous intravenous infusion for 14 days. Doses of the drug ranged from 10 mg/m2/day to 35 mg/m2/day, with most patients receiving 16.5 mg/m2/day. In two patients, the drug was stopped early in the course of treatment because of thrombocytopenia. Thirteen patients completed therapy according to protocol. Three of 13 patients demonstrated a partial response to therapy. Of these three patients, one had an increase in platelet and absolute neutrophil counts, while the other two no longer required support with red cell transfusions. The drug was well tolerated and significant myelosuppression did not occur in most patients. Low-dose 5-azacytidine appears to have activity in the treatment of primary MDS and future studies should consider evaluation of this drug in combination with hematopoietic growth factors.